Introduction to Games of Chance
Primary 4 · Mathematics
Introduction to Games of Chance
Lesson 1 of 4
25 min
Let's begin
Before the football match at break, Niyonzima, the referee, tosses a 100 Frw coin to decide which team kicks off. "Heads, your team starts. Tails, ours does," he says. "Is that fair?" asks Keza.
In a game of chance, nobody can know the result before it happens. Today you will learn how to talk about chance and how to tell whether a game is fair.
Some things are sure to happen and some can never happen. Most things are somewhere in between.
A coin has two sides. We call one side heads and the other tails. When you toss a coin, there are 2 possible outcomes: heads or tails. Each result that can happen is called an outcome.
A fair coin is just as likely to land heads as tails. So the chance of heads is 1 out of 2. We can write this as the fraction 12.
A game is fair when every player has the same chance of winning. In Niyonzima's toss, one team wins with heads and the other with tails. Each team has 1 winning outcome out of 2. So the toss is fair.
Uwase tossed a coin 20 times and made a tally. She got 11 heads and 9 tails. That is not exactly 10 and 10, and that is normal! Chance does not share things out perfectly in a few tosses. If you toss many more times, the numbers of heads and tails usually get closer to half each.
Suppose you get heads 4 times in a row. On the next toss, the chance of heads is still 1 out of 2. The coin does not remember what happened before.
Tip
Fair means the same chance for everyone. Count the winning outcomes for each player. If the counts are equal, the game is fair.
Work each one in your exercise book first. Then tap Show answer to check.
What are the two possible outcomes when you toss a coin?
Answer: Heads and tails.
Is it impossible, unlikely, equally likely, likely or certain that a tossed coin lands tails?
Answer: Equally likely. The chance is 1 out of 2.
Is it impossible, unlikely, equally likely, likely or certain that the sun will set this evening?
Answer: Certain.
Mugisha tossed a coin 10 times and got 6 heads. Does that mean the coin is unfair?
Answer: No. In a few tosses the results are rarely exactly half and half.
Gatete says: "Heads, I win. Tails, you lose." Is this game fair?
Answer: No! Both outcomes mean Gatete wins. The other player has no winning outcome at all.
What you learned today
Sources and credits
The stories, Rwandan examples, diagrams and practice questions were written by Ganzaa.
Quick check
Match each event to its chance word.
Tap one on the left, then its partner on the right.
